1. Field of the Invention
This invention relates to a display apparatus comprised of a display element arranged on a panel substrate.
2. Description of Related Art
As a flat type display apparatus, a liquid crystal display (extraneous light emission display), an organic EL (electroluminescence) display and a plasma display (PDP) are being put to use.
FIGS. 1 and 2 show an illustrative structure of an organic EL display, among the above-mentioned plural displays, which recently is attracting particular notice. An illustrative structure of the organic electroluminescence (EL) display is shown in FIGS. 1 and 2. This organic EL display 20 is comprised of a transparent substrate 21, a plurality of transparent electrodes 22, arranged in stripes, as anodes, on the transparent substrate 21, a plurality of organic layers 23, each made up of a positive hole transporting layer and a light emitting layer, formed at right angle to the transparent electrodes 22 and a plurality of cathodes 24 formed on the organic layers 23, whereby organic EL devices are formed at the intersecting points of the transparent electrodes 22 and the cathodes 24 to form a light emitting area A comprised of a matrix of these organic EL devices, and a contact electrode B is formed in the vicinity of the light emitting area A for taking out the light emitting area to an external circuit or to an inner drive circuit.
Although not shown, in the organic EL display 20, an insulating layer is usually provided between the neighboring transparent electrodes 22, whereby the shorting across neighboring transparent electrodes 22 and that across the transparent electrodes 22 and the cathodes 24 may be prevented from occurring.
In such organic EL display, there is, for example, a single hetero type organic EL device 30, shown in FIG. 3, as an organic EL device constructed at an intersection 30 includes a transparent substrate 21, such as a glass substrate, on which there are sequentially formed a transparent electrodes 22 of, for example, ITO (indium tin oxide), an organic layer 23, made up of a positive hole transporting layer 23a and a light emitting layer 23b, and a cathode 24, arranged in this order.
If, in the above-described organic EL device 30, a positive voltage and a negative voltage are applied to the anodes and cathodes, the positive holes implanted from the anodes reach the light emitting layer 23b through the positive hole transporting layer 23a, whilst the electrons implanted at the cathode reach the light emitting layer 23b, so that electron-positive hole recombination occurs in the light emitting layer 23b. The light of a pre-set wavelength is emitted at this time and radiated from the side transparent substrate 21 to outside as indicated by arrow in FIG. 3.
So, a wide variety of display apparatuses, employing a wide variety of display devices, are being developed and put to practical use.
However, although the liquid crystal display device is of low voltage and low power consumption and hence may be driven by a general-purpose integrated circuit, liquid crystal display is low in response speed, so that an image needs to be displayed by an active matrix system in which TFTs (thin-film transistors) are built into each pixel, thus raising the production cost.
In an autogenous light emission display device, such as organic EL device or plasma display, the display dynamic range is wide such that a bright image can be displayed. However, the driving voltage is as high as approximately 100 V, thus presenting driving difficulties in the general-purpose integrated circuit.
In the screen size is to be increased with the organic EL device, it is not possible with the conventional passive matrix system to cause the entire surface of the large-sized display device to emit light by reason of voltage drop caused by the wiring resistance of the drive circuit mounted in the vicinity of the display device.
It is therefore an object of the present invention to provide a display device in which it is possible to increase the screen size.
The present invention provides a display apparatus which enables the display screen to be increased in size. The display apparatus includes a panel substrate operating as a display screen, plural display devices arranged in a matrix on the panel substrate, and a drive circuit substrate having a drive circuit for driving each display device. The panel substrate is subdivided into plural areas by a driving wiring adapted for driving the display devices, and a plurality of the drive circuit substrates are provided in association with the respective areas.
According to the display apparatus of the present invention, the driving wiring can be shorter in length by subdividing the panel substrate carrying the display devices and the drive circuit substrate to eliminate voltage drop caused by the resistance of the driving wiring to provide for stable driving of the display devices.
That is, with the display apparatus according to the present invention, in which the drive circuit substrate for driving the display devices is subdivided to reduce the length of the wiring to eliminate the voltage drop ascribable to the wiring resistance to provide for stable driving of the display devices. By subdividing the panel carrying the display devices and the drive circuit substrate, maintenance or repair may be performed from area to area to keep the quality of the display. According to the present invention, if the display screen is increased in size, the display devices can be driven in stability to realize a high quality display apparatus.